The purpose of this study is to compare the immediate and long term (up to 5 years) immunogenicity and safety of GSK Biologicals' MenACWY-TT vaccine when given as a single dose or as 2 doses to toddlers aged 12 to 14 months. Also, this study will also assess if co-administration of GSK Biologicals' MenACWY-TT with the booster dose of Pfizer's Prevenar 13 adversely impacts the immunogenicity of either of the vaccines.